# Get rid of all line endings, regardless of which flavor they are
    (my $line = shift) =~ s/[\r\n]//g;

##</code><code>##

    # does this look like a S1, S2, or S3 record? These are the only ones that
    # carry an actual data payload. Other record types do not, so just ignore
    # them.
    return unless $line =~ m/^s([1-3])(\p{IsXDigit}{2})(\p{IsXDigit}{4,6,8})(\p{IsXDigit}+)(\p{IsXDigit}{2})$/;

    my ($type, $count, $address, $data, $cs) = ($1, $2, $3, $4, $5);

    # does the address length match the record type?
    return unless length $address == 2 * ($type + 1);

    # Make sure the COUNT field makes sense. It should represent the sum of
    # address, data, and checksum fields, in bytes
    return unless hex($count) == (length($address) + length($data) + length($cs)) / 2;

##</code><code>##

    my $compCs = hex($count);
    foreach my $nibble ($address =~ m/../g, $data =~ m/../g) {
        $compCs += hex($nibble);
    }

##</code><code>##

    my $compCs = hex($count);
    $compCs += hex($_) foreach($address =~ m/../g, $data =~ m/../g);

##</code><code>##

    my $compCs = reduce { $a + $b }
                 map    { hex $_  }
                 ($count, $address =~ m/../g, $data =~ m/../g);

##</code><code>##

    my $status = $compCs == hex($cs);

##</code><code>##

use List::Util;

# ...

# Parse a single line of S-record, validate the line, and extract the address
# and data fields. Return a list of three scalars:
#  1. TRUE if extraction was successful, FALSE otherwise (i.e. not a valid data
#     carrying S-record, bad s-record length, bad s-record checksum).
#  2. The address of the line's payload, as a string.
#  3. The data of the line's payload, as a string.
sub ProcessSrecLine
{
    # Get rid of all line endings, regardless of which flavor they are
    (my $line = shift) =~ s/[\r\n]//g;

    # does this look like a S1, S2, or S3 record? These are the only ones that
    # carry an actual data payload. Other record types do not, so just ignore
    # them.
    return unless $line =~ m/^s([1-3])(\p{IsXDigit}{2})(\p{IsXDigit}{4,6,8})(\p{IsXDigit}+)(\p{IsXDigit}{2})$/;

    my ($type, $count, $address, $data, $cs) = ($1, $2, $3, $4, $5);

    # does the address length match the record type?
    return unless length $address == 2 * ($type + 1);

    # Make sure the COUNT field makes sense. It should represent the sum of
    # address, data, and checksum fields, in bytes
    return unless hex($count) == (length($address) + length($data) + length($cs)) / 2;

    # Make sure the checksum makes sense. It is the two's complement of
    # the sum of count, address, and data fields
    my $compCs = reduce { $a + $b }
                 map    { hex $_  }
                 ($count, $address =~ m/../g, $data =~ m/../g);

    $compCs %= 256;
    $compCs = 255 - $compCs;

    # if the checksum actually matches, then call it a good S-record
    my $status = $compCs == hex($cs);

    return ($status, $address, $data);
}

##</code><code>##

    # ...

    # if the checksum actually matches, then call it a good S-record
    return ($compCs == hex($cs), $address, $data);